// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_
#define MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_

#include <memory>
#include <string>
#include <unordered_set>
#include <utility>

#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/memory/scoped_vector.h"
#include "base/observer_list.h"
#include "base/threading/thread.h"
#include "build/build_config.h"
#include "media/audio/audio_device_name.h"
#include "media/audio/audio_manager.h"
#include "media/audio/audio_output_dispatcher.h"

#if defined(OS_WIN)
#include "base/win/scoped_com_initializer.h"
#endif

namespace media {

class AudioOutputDispatcher;

// AudioManagerBase provides AudioManager functions common for all platforms.
class MEDIA_EXPORT AudioManagerBase : public AudioManager {
public:
    ~AudioManagerBase() override;

    // AudioManager:
    base::string16 GetAudioInputDeviceModel() override;
    void ShowAudioInputSettings() override;

    void GetAudioInputDeviceDescriptions(
        AudioDeviceDescriptions* device_descriptions) final;
    void GetAudioOutputDeviceDescriptions(
        AudioDeviceDescriptions* device_descriptions) final;

    AudioOutputStream* MakeAudioOutputStream(
        const AudioParameters& params,
        const std::string& device_id,
        const LogCallback& log_callback) override;
    AudioInputStream* MakeAudioInputStream(
        const AudioParameters& params,
        const std::string& device_id,
        const LogCallback& log_callback) override;
    AudioOutputStream* MakeAudioOutputStreamProxy(
        const AudioParameters& params,
        const std::string& device_id) override;

    // Listeners will be notified on the GetTaskRunner() task runner.
    void AddOutputDeviceChangeListener(AudioDeviceListener* listener) override;
    void RemoveOutputDeviceChangeListener(AudioDeviceListener* listener) override;

    AudioParameters GetDefaultOutputStreamParameters() override;
    AudioParameters GetOutputStreamParameters(
        const std::string& device_id) override;
    AudioParameters GetInputStreamParameters(
        const std::string& device_id) override;
    std::string GetAssociatedOutputDeviceID(
        const std::string& input_device_id) override;
    std::unique_ptr<AudioLog> CreateAudioLog(
        AudioLogFactory::AudioComponent component) override;

    void SetMaxStreamCountForTesting(int max_input, int max_output) final;

    // AudioManagerBase:

    // Called internally by the audio stream when it has been closed.
    virtual void ReleaseOutputStream(AudioOutputStream* stream);
    virtual void ReleaseInputStream(AudioInputStream* stream);

    // Creates the output stream for the |AUDIO_PCM_LINEAR| format. The legacy
    // name is also from |AUDIO_PCM_LINEAR|.
    virtual AudioOutputStream* MakeLinearOutputStream(
        const AudioParameters& params,
        const LogCallback& log_callback)
        = 0;

    // Creates the output stream for the |AUDIO_PCM_LOW_LATENCY| format.
    virtual AudioOutputStream* MakeLowLatencyOutputStream(
        const AudioParameters& params,
        const std::string& device_id,
        const LogCallback& log_callback)
        = 0;

    // Creates the input stream for the |AUDIO_PCM_LINEAR| format. The legacy
    // name is also from |AUDIO_PCM_LINEAR|.
    virtual AudioInputStream* MakeLinearInputStream(
        const AudioParameters& params,
        const std::string& device_id,
        const LogCallback& log_callback)
        = 0;

    // Creates the input stream for the |AUDIO_PCM_LOW_LATENCY| format.
    virtual AudioInputStream* MakeLowLatencyInputStream(
        const AudioParameters& params,
        const std::string& device_id,
        const LogCallback& log_callback)
        = 0;

    // Get number of input or output streams.
    int input_stream_count() const
    {
        return static_cast<int>(input_streams_.size());
    }
    int output_stream_count() const { return num_output_streams_; }

protected:
    AudioManagerBase(
        scoped_refptr<base::SingleThreadTaskRunner> task_runner,
        scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
        AudioLogFactory* audio_log_factory);

    // Releases all the audio output dispatchers.
    // All audio streams should be closed before Shutdown() is called.
    // This must be called in the destructor of every AudioManagerBase
    // implementation.
    void Shutdown();

    void SetMaxOutputStreamsAllowed(int max) { max_num_output_streams_ = max; }

    // Called by each platform specific AudioManager to notify output state change
    // listeners that a state change has occurred.  Must be called from the audio
    // thread.
    void NotifyAllOutputDeviceChangeListeners();

    // Returns user buffer size as specified on the command line or 0 if no buffer
    // size has been specified.
    static int GetUserBufferSize();

    // Returns the preferred hardware audio output parameters for opening output
    // streams. If the users inject a valid |input_params|, each AudioManager
    // will decide if they should return the values from |input_params| or the
    // default hardware values. If the |input_params| is invalid, it will return
    // the default hardware audio parameters.
    // If |output_device_id| is empty, the implementation must treat that as
    // a request for the default output device.
    virtual AudioParameters GetPreferredOutputStreamParameters(
        const std::string& output_device_id,
        const AudioParameters& input_params)
        = 0;

    // Appends a list of available input devices to |device_names|,
    // which must initially be empty.
    virtual void GetAudioInputDeviceNames(AudioDeviceNames* device_names);

    // Appends a list of available output devices to |device_names|,
    // which must initially be empty.
    virtual void GetAudioOutputDeviceNames(AudioDeviceNames* device_names);

    // Returns the ID of the default audio output device.
    // Implementations that don't yet support this should return an empty string.
    virtual std::string GetDefaultOutputDeviceID();

private:
    struct DispatcherParams;
    typedef ScopedVector<DispatcherParams> AudioOutputDispatchers;

    class CompareByParams;

    // These functions assign group ids to devices based on their device ids.
    // The default implementation is an attempt to do this based on
    // GetAssociatedOutputDeviceID. Must be called on the audio worker thread
    // (see GetTaskRunner()).
    std::string GetGroupIDOutput(const std::string& output_device_id);
    std::string GetGroupIDInput(const std::string& input_device_id);

    // Max number of open output streams, modified by
    // SetMaxOutputStreamsAllowed().
    int max_num_output_streams_;

    // Max number of open input streams.
    int max_num_input_streams_;

    // Number of currently open output streams.
    int num_output_streams_;

    // Track output state change listeners.
    base::ObserverList<AudioDeviceListener> output_listeners_;

    // Contains currently open input streams.
    std::unordered_set<AudioInputStream*> input_streams_;

    // Map of cached AudioOutputDispatcher instances.  Must only be touched
    // from the audio thread (no locking).
    AudioOutputDispatchers output_dispatchers_;

    // Proxy for creating AudioLog objects.
    AudioLogFactory* const audio_log_factory_;

    DISALLOW_COPY_AND_ASSIGN(AudioManagerBase);
};

} // namespace media

#endif // MEDIA_AUDIO_AUDIO_MANAGER_BASE_H_
